elephant seal

A large pinniped, speciesmirounga angustirostris. Males may grow to two and a half tons and over seventeen feet in length. The common name "Elephant Seal" is derived from the adult male's long proboscis, which can be 1-2 feet in length. Males fight for access to groups of females, who in turn fight for the best spots on the beach to give birth to their pups. Females are only in estrus for one to three days a year, so the males who have fought their way closest to them are the ones who pass on their genes. Only about one half of one percent of males reproduce in their lifetimes. (So quit your whining.)
Females usually give birth to only one pup per year. They nurse the pup for thirty days, then return to the ocean. The pup may triple its weight during the nursing period. When mom leaves, the other females usually chase the pup out of the "harem", or group of nursing females and their young. A few pups successfully sneak back into the harem and fool a female into letting them nurse; they may even be "adopted". These pups are referred to as "superweaners" or "double mother-sucklers" by researchers. A superweaner can reach 300 pounds, at which point it can hardly move.
With mom gone, the pups hang out on the beach for a few months without eating or drinking. Then they teach themselves to swim and feed. Eventually, they leave the beach to swim a gauntlet of great white sharks waiting for a snack. 50% of all pups survive their first year.
These seals can dive for well over an hour to depths of more than 5,000 feet. They only come ashore twice a year: once to mate, and once to molt. When they are on shore they don't eat or drink. Males may go three months without eating while hanging around waiting to mate with a female. Females who come ashore, give birth and nurse may lose 50% of their body mass in a little over a month.